I run an online game that uses paypal as the primary method of purchasing additional turns and upgrades, and I can tell you that paypal is a huge PITA. It's not FDIC insured, and they bend you over on the charges (depending on the transaction amount, up to 15% of the total). All this means is that "your" money isn't actually yours while it's in paypal's hands, and there is no guarantee that you'll get the money should paypal decide to lock the account down (which happens more regularly than they admit).
Technically, in your situation, a check would be the same as a paypal transaction in that you can always stop payment on a check. A money order, on the other hand, is a bad idea if you're even the slightest bit uncomfortable.